You definitely need a new gasket. I prefer replacing the filter but it's really up to you, as the car owner. Inspect it and replace if dirty. I only use OEM parts and buy them from IoS (Infiniti of Scottsdale), a.k.a. "InfinitiPartsUSA.com" (see link below). So I can't say anything about the quality of those brands. The crush washer is a copper gasket, same as the one used on the oil drain plug. It's very important to take note of the mounting bolts position for the filter as the length varies. One of them is actually a NUT. Use good lighting and take pictures, if possible.
http://www.infinitipartsusa.com/partloc ... atalogid=0
As in my previous posting, the recommended fluid for your 96 I30 is Nissan Matic-D but Dexron III will do. Dexron VI supersedes Dex III and is much better. For as long as the ATF conforms with Dex VI spec, then it is preferable than Dex III. You can also use Mobil 1 or Amsoil ATF. If you find name brand expensive, Super Tech Dex VI at Walmart is relatively cheap. Once you are done with the drain-and-refill, add a bottle of LubeGard (Red, not black) ATF Protectant. Recheck ATF level and add fluid as required.